Forecast in line chart for next 4 week

[paolojolly]

Hi, I'm not very experienced in QlikView and I need help to create a line chart that tracks for the next 4 weeks a trend line starting from historical data(file DATA.xls)

The end result should be something like

where Sales is history week value

I think I should use the functions linest_m and linest_b but I do not know them very well

Can someone help me?

thanks